This invention relates to novel processes for the preparation of intermediates in the synthesis of the quinoline antibiotic 7-(1.alpha.,5.alpha.,6.alpha.)-(6-amino-3-azabicyclo[3.1.0]hex-3-yl)-1-(2, 4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid and related antibiotic compounds. The quinoline antibiotic 7-(1.alpha.,5.alpha.,6.alpha.)-(6-amino-3-azabicyclo[3.1.0]hex-3-yl)-1-(2, 4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid has the chemical formula ##STR2## This compound and related azabicyclo quinoline carboxylic acids that exhibit antibacterial activity are referred to in U.S. patent application Ser. No. 07/551,212, filed on Jul. 11, 1990 and World Patent Application WO 91/02526, filed on Aug. 16, 1989 and published on Mar. 7, 1991. Both of the foregoing applications are assigned in common with the present application and are incorporated herein by reference in their entirety.
The novel methods of this invention may be used to prepare compounds of the formula ##STR3## which are intermediates in the synthesis of the quinoline antibiotic of the formula I and the azabicyclo quinoline carboxylic acid antibiotics referred to above. The methods by which compounds of the formula VII may be converted into such antibiotic compounds are set forth in detail in U.S. patent application Ser. No. 07/551,212 and World Patent Application WO 91/02526.